/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.google.code.motoo.codec;

import com.google.code.motoo.core.IoBuffer;
import com.google.code.motoo.core.IoSession;

/**
 * 循环的将IoBuffer里面的数据编码完毕，并且将已使用的数据从IoBuffer中清除出去
 * @author linfengqi
 * @version 1.0  May 11, 2009
 */
public abstract class CumulativeProtocolDecoder implements ProtocolDecoder{

	public void decode(IoSession session, IoBuffer in, ProtocolDecoderOutput out) throws Exception {
		int start = 0;
		int end = 0;
		while (in.hasRemaining()) {
			boolean finish = doDecode(session, in, out);
			if (finish) {
				end = in.position();
			} else {
				break;
			}
		}

		if (start == end)
			in.recover();
		else
			in.trim(start, end);
	}

	protected abstract boolean doDecode(IoSession session, IoBuffer in, ProtocolDecoderOutput out) throws Exception;

}
